30 minutes in the sun is enough to get your daily dose iirc.

I think I get 30 minutes from going outside for lunch and walking to my car, driving, taking out the trash, getting my mail, etc.

I’m not sure how correct that is. Particularly in certain countries and especially in winter. I get out for more than 30mins every day and my levels are deficient when I tested.

It also depends on your skin color and latitude.

it varies greatly person to person.

+1. I was deficient, despite averaging 7000 steps per day (80 min of walking). I also live in seattle and stay bundled up

Copenhagen in the winter will have you sit outside all day. All 6 hours of it.

In order to produce vitamin D, your skin needs continuous time in the sun to fully react with sunlight.

30 minutes of continuous chemical reaction will have vastly different effect than a reaction that stops & starts repeatedly, for a sum total of 30 minutes.

You actually are going to synthesize _more_ vitamin D if you do fractionated exposure.

That's because vitamin D synthesis is an equilibrium reaction, UV drives backward and forward reactions. So you'll get more vitamin D if you expose your skin to the sun for a few minutes, then let the synthesized vitamin to diffuse out of the skin layer, and then expose yourself again.

That makes sense. Thanks for explaining.

and/or eat a lot of food rich in Vitamin D.

30 minutes with large skin contact. Take off your shirt or have a tank top.

That's enough for skin cancer where I live. 5min tops.

It's enough for frostbite where I live.

It’s enough for mosquitoes where I live.

Not trying to argue; just chipping in:

I regularly sit outside with my shirt off in ~20F weather and don't get cold enough to have to go inside.

Direct sunlight makes all the difference. With the sun, sub freezing air temperatures can actually leave you feeling quite warm.

I guess that depends on time of day, and ozone health, I assume you live in Australia?

I live in the Middle East and the uv index in the am (before 9am) in direct sunlight isn’t that crazy.

I was locked in a windowless room for 10 year straight. What I don't know is if the long-term deprivation of vitamin D produces any long-term nonreversible damage. Does anyone know?

Life produces long-term non-reversible damage, I'm afraid.

But up to a certain point it's the complete opposite.

Unfortunately that point is around 18 years of age.

This is one thing I think is not appreciated enough about WFH. It can, in some cases mean work from outdoors for some period of time. I don’t mean relaxing in the sunshine and pretending to work. I mean working your ass off outside and moving the needle for your organization.

I’m sorry, Elon is waaay smarter and more capable than I am but he is empirically wrong about his anti WFH bias.

WFH what?

"Work from home"

Out of curiosity, and if you don't mind sharing, what was your staring position?

I ask, because even if they never invest a cent in your personal ventures, it is a very significant boost to to have wealthy parents who provide both broad access to formal and informal education, valuable networking, and a dependable safety net. Saying someone with those advantages is "more capable" when comparing them to the average First Worlder (let alone the average human being) is a sort of perceptual bias that seems unfortunately common.

I have no excuses.

or it could mean not leaving your house for weeks at a time. At least when you go to the office you have to leave your home and go to the office and that in theory means time outside.

So, it is better to be forced to go somewhere that they don’t want to go so that they are forced to go outside for a few minutes (or seconds even).

I sincerely hope you meant that figuratively. If not, I'm sorry, and I hope you managed to stay relatively sane during those years.

Jail, sadly. No windows, no fresh air. Took me almost 10 years to get the bond money together to get out. I was only in there because I couldn't get access to my money from inside the jail.

There are plenty of sources of vitamin D outside of sunlight.

I don't know if you're playing up being a homebody or if something horrible happened to you.

Jail, sadly. No windows, no fresh air. Took me almost 10 years to get the bond money together to get out. I was only in there because I couldn't get access to my money from inside the jail.

I may have a clue: you are most likely to suffer no harm at all. Certainly not as far as sunlight/Vit D goes. ( though windows can be good for things like diluting foul air). Read the works of Prof Trevor Marshall for a lengthy explanation.

Curiosity: How did you land up in the windowless situation?

Jail, sadly. No windows, no fresh air. Took me almost 10 years to get the bond money together to get out. I was only in there because I couldn't get access to my money from inside the jail.

Gosh. I had a look at your other posts. It's terrible what's happened to you.

Since you appear to have seen the underbelly of society you make want to look at my profile and read link I've put on my profile. It may sound a little predatory when I suggest that you look at my profile, but so be it.

If my laptop screen were legible in direct sun, I'd be out there. Wifi and headphones.

Sadly the laptop's too small and Chrome's too power-hungry for solar power to be an option: ⅓m width * ¼m length * 158W/m2 solar = 13W out of 67W to run it, or 19%.

How do you factor in skin cancer with this mindset?

While I love being outside, I always wear hats, hoods and jackets to protect my skin.

Also cataracts would also be a problem.

I wonder what stone age people did about skin cancer. Nothing, I assume.

Skin cancer is one of the more relatively common cancers in young people, but first diagnosis still increases sharply with age. Life expectancy at age 15 (so, without the 60% infant/child mortality) in the Paleolithic was apparently 54 years.

https://www.cancerresearchuk.org/health-professional/cancer-...

Ihttps://en.m.wikipedia.org/wiki/Life_expectancy

Stone age people used sunscreen. It wasn't anywhere near as effective as modern sunscreen. Presumably they were less concerned about skin cancer and more concerned about the immediate effects of a sunburn

Bro what - they did not use sunscreen - where did they get titanium and zinc?

Not seeing titanium, zinc, oxybenzone, octinoxate, octisalate, or avobenzone.

That’s not our sunscreen.

The History of Sunscreen

https://jamanetwork.com/journals/jamadermatology/article-abs...

Also not seeing titanium, zinc, oxybenzone, octinoxate, octisalate, or avobenzone.

Who is defining the word "sunscreen" so narrowly to these compounds?

All you are doing is listing modern formulations, some of which are not even generally regarded as safe anymore.

Point being that ancients did not use sunscreen or anything remotely close to the formulae we have today - what we have today was roughly defined 100 years ago and has some serious consequential effects on the endocrine system and more.

> Point being that ancients did not use sunscreen

The statement being made by others is that "ancients" applied a topical substance to protect their skin from harmful effects of the sun, most would call that sunscreen[0] but use whatever word you prefer.

> anything remotely close to the formulae we have today

No one is making this claim.

[0] https://dictionary.cambridge.org/dictionary/english/sunscree...

The statement was about skin cancer, and the implication is that they did nothing about it.

Sunscreen is a 20th century term, and modern sunscreen as we know it came into use in the mid-20th century.

I don’t think they lived long enough for it to be a problem.

They were a lot longer outside than modern people though.

Outside != full sun.

Sitting in tree shade won't give you skin cancer.

How much UVA/UVB gets filtered out from shade under a tree? And how much vitamin D are we getting to make sitting in the shade worthwhile?

Cancer is a bigger problem now because we have learned how to deal with other diseases.

Well yeah.. just like wild animals which break a leg, catch a serious diseases etc. they can't do anything about it and die.

Don’t know about Stone Age, but look at the clothing worn by desert tribes. Loose fitting clothes covering arms and legs, so e kind of covering on the head.

I think the dangers of over exposure to the sun have long been known and only recent generations think shorts and T shirts in direct sun for long amounts of time is a good idea.

they were dead by 40, skin cancer usually takes a little longer to show up and kill you.

How long did Stone Age people live? I thought most people died at like 40? I’m planning on living longer than that.

I just set up on my deck with a deck umbrella and an external 32” monitor.

It works well but it would actually be nice to have polarized glasses that improve the situation instead of making it worse.

I feel like this is a VR headset's killer app - once the DPI gets there, it will let me bask in the sun while still being productive. I can't wait.

So the advice to "touch grass" was actually well intentioned?

I'm actually rather annoyed by the recent trend of basic things like "go touch grass" or "go exercise every day" or "eat more fiber" being scientifically validated, because it's stripping away any and all excuses for me not going outside/exercising/eating well/etc.

Like damn, I knew I was supposed to do such things already, but it's the difference between mom saying to eat your veggies vs. mom slamming down a stack of scientific paper about why not eating veggies will literally kill you or whatever.

If it helps, you can just take a vitamin D supplement and stay inside, avoiding some major health risks like skin cancer and death by vehicular accidents.

Sunlight does way more than let the skin convert this specific chemical. You could look up photobiomodulation, for example.

Sure, get a sun lamp.

Get an under-desk elliptical, vit D oil drops, bake bread with 50% wheat flour replaced with almond/coconut/sunflower/pumpkin/etc meal.

Wham, unhealthy lifestyle eradicated at almost no behavioural cost.

Or, install some full-spectrum daylight-mimicing LED lights. These are not that easy to find, you want to use the CCT and CRI ratings to match sunlight as closely as possible.

https://www.uvm.edu/news/extension/tips-choosing-grow-lights

They're kind of hard to find, the optimal values are 6500K for CCT and as close to 100 as possible for CRI, which matches the peak value and the overall spectrum of natural sunlight. One option appears to be the NorthLux™ 95 CRI T8 LED Tube (kind of pricy though, and will need a specialized ballast fixture, also a bit pricy).

Vitamin D needs UV, not just light.

You _can_ install UV diodes, but then you have a whole another can of worms. A point source of UV can damage eyes much more easily, and if you forget to turn it off, you can expect a nasty sunburn.

Being outdoors is almost always better than being indoors and people do need to get out more but that’s not the solution to a problem brought about by bodies being adapted to sub-Saharan latitudes but living north or south of the 37th parallel.

https://www.health.harvard.edu/staying-healthy/time-for-more...

An hour a day buck-ass naked, isn’t enough if you don’t live along the equator.

For many northern and southern latitudes where many people live if you affixed yourself to a rotating pole and rotisserie’d yourself from sunrise to sunset while naked every day, then for 4-9 months out of the year you would be D deficient.

I’m outdoors more than most and if I don’t supplement my levels fall into the mid-20s ng/mL, below the standard range of 30-100.

And no matter how many millions of studies repeat verbatim the importance of vitamin d people still neglect it.

No but you should go out a couple of times a week for a walk and get some sun. the body is amazingly good at manufacturing vitamin d in a short amount of time especially with full sunlight. You don't have to get skin cancer though.

I know several women that go outside and take walks for their vitamin d, but slather on sunscreen which blocks the process. No matter how many times I tell them it's a worthy trade-off, they won't go outside without.

I'm 38, and have never worn sunscreen outside of going to the beach for a whole day. I often get compliments from women about my face, and they're shocked to hear I never wear sunscreen or moisturize. It's almost like not putting chemicals on your face is good for you.